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09-27-2023, 09:07 PM   #1
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Has anybody replaced their DA 645 28-45mm F4.5 with the HD Pentax-D FA 645 35mm 3.5 ?

I think the DA 645 28-45mm F4.5 ED AW is a great lens but it is a heavy beast, so heavy in fact that I find myself reaching for my 645Z less and less these days

And that is a shame because the files produced by the 645Z are second to none.

I'm wondering if anybody has replaced the DA 645 28-45mm F4.5 ED AW with the HD Pentax-D FA 645 35mm F3.5 AL [IF]

I shoot primarily Landscapes.

Thanks.

09-27-2023, 10:21 PM - 1 Like   #2
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I haven't replaced mine because it is such a good lens and with a very versatile focal length range. Instead I added the 25mm and the FA35mm but for different reasons. The 25mm is very wide and does give a large field of view which also captures less detail, by definition. The 35mm is a nice wide angle and conveniently light weight for "on the go" but it has the same wide angle compression effect. The 28-45 is the only lens that covers the wide angle view, with the resulting compression, and you can reach an almost zero compression when zoomed to 45mm.

If you want to cut down on weight then you can consider the 35mm and dfa 50mm as a combo, which will give you an almost equivalent range. Probably the same weight in total, but spread out.

Personally I don't like wide angle lenses for landscapes, I think it loses the finer details that is capable to capture in MF. I try to stay with focal lengths longer than 45mm. It also gives less compression effects. The compression I'm referring to is the 'zoom' effect you see on the sides of wide angle shots. Those are nice for effects, but in landscapes it annoys me. Just my own preference....

Now for some whining ---- I have no idea why they bothered with stabilization in the 28-45. It is a wide angle for crying out loud. The lens could have been substantially smaller and lighter without the stabilization, and perhaps could have been a dfa at the same time. -- end of whining...

Last edited by TDvN57; 09-27-2023 at 10:23 PM. Reason: Typo
09-28-2023, 02:24 AM - 2 Likes   #3
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I use the A 35/3.5

...and find it superb for landscapes (including cityscapes, etc.)

As to your specific question, I never considered the DA 28-45 simply because I just don't enjoy working with zoom lenses, and also the weight and bulk of it would just put me off (even if I do shoot from a tripod most of the time).

Marco
09-28-2023, 10:24 AM   #4
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QuoteOriginally posted by TDvN57 Quote
I try to stay with focal lengths longer than 45mm. It also gives less compression effects. The compression I'm referring to is the 'zoom' effect you see on the sides of wide angle shots.

Now for some whining ---- I have no idea why they bothered with stabilization in the 28-45. It is a wide angle for crying out loud. The lens could have been substantially smaller and lighter without the stabilization, and perhaps could have been a dfa at the same time. -- end of whining...
I believe you mean distortion, not compression.

And yes, I agree that stabilization is an oddity for any wide angle or even normal in the 50-75mm range.

09-28-2023, 10:51 AM - 1 Like   #5
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QuoteOriginally posted by Alex645 Quote
I believe you mean distortion, not compression.

And yes, I agree that stabilization is an oddity for any wide angle or even normal in the 50-75mm range.

You are right I don't want to call it distortion because that sounds like a flaw, which it isn't. It is the inherent character of a lens that increases as you go wider with smaller focal lengths. I see it as a uneven compression over the width of the image. The sides of the image compresses so much of the field of view that you can almost use it as a zoom as you get closer to an object.

Please don't misunderstand me, I'm not speaking out against landscapes with wide angle lenses, I was only mentioning my personal preference.
09-28-2023, 04:29 PM   #6
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Perhaps what is being observed is the difference between f*tan(theta) and f*theta lens assemblies. The former is what a pinhole camera naturally does with a flat focal plane; the latter is what your eye and head movement creates in your mental image of a scene. Both f-theta and f-tan-theta lens assemblies can be designed and fabricated, but I vaguely recall that f-theta is more difficult for short effective focal lengths when one can't put glass close to the focal plane because there is a prohibited space occupied by a mirror assembly.
09-28-2023, 08:21 PM - 1 Like   #7
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QuoteOriginally posted by kaseki Quote
Perhaps what is being observed is the difference between f*tan(theta) and f*theta lens assemblies. The former is what a pinhole camera naturally does with a flat focal plane; the latter is what your eye and head movement creates in your mental image of a scene. Both f-theta and f-tan-theta lens assemblies can be designed and fabricated, but I vaguely recall that f-theta is more difficult for short effective focal lengths when one can't put glass close to the focal plane because there is a prohibited space occupied by a mirror assembly.
I always appreciate your technical comments, it reminds me to acknowledge how little I know (in a nice way) about the technology behind the image making machines we play with :-)

My approach is simply what I see, either a picture looks plausibly realistic, as if i stood there and looked at the scene myself, or it looks slighly off, perhaps I cant define it. So nothing wrong with it, just my personal taste. :-)

Shall we come back to the OP's original question?

10-01-2023, 06:49 AM - 3 Likes   #8
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Well, I bought a 480 $ 645 FA 35 mm f/3.5 on eBay last year and I found it "extremely satisfying" in landscape picture-taking. Usable between f/6.3 and f/32 to attain splendid edge-to-edge sharpness.

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